Composites of Laponite and Cu–Mn Hopcalite-Related Mixed Oxides Prepared from Inverse Microemulsions as Catalysts for Total Oxidation of Toluene

Composites of Laponite and Cu–Mn hopcalite-related mixed oxides, prepared from hydrotalcite-like (Htlc) precursors obtained in inverse microemulsions, were synthesized and characterized with XRF, XRD, SEM, TEM, H2 temperature-programmed reduction (TPR), and N2 adsorption/desorption at −196 °C. The Htlc precursors were precipitated either with NaOH or tetrabutylammonium hydroxide (TBAOH). Al was used as an element facilitating Htlc structure formation, and Ce and/or Zr were added as promoters. The composites calcined at 600 °C are mesoporous structures with similar textural characteristics. The copper–manganite spinel phases formed from the TBAOH-precipitated precursors are less crystalline and more susceptible to reduction than the counterparts obtained from the precursors synthesized with NaOH. The Cu–Mn-based composites are active in the combustion of toluene, and their performance improves further upon the addition of promoters in the following order: Ce < Zr < Zr + Ce. The composites whose active phases are prepared with TBAOH are more active than their counterparts obtained with the use of the precursors precipitated with NaOH, due to the better reducibility of the less crystalline mixed oxide active phase.

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Hydrogen Adsorption Capacity Investigation of Ni-Co-Al Mixed Oxides

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.917.360 ◽

2014 ◽

Vol 917 ◽

pp. 360-364 ◽

Cited By ~ 4

Author(s):

M. Abdus Salam ◽

Suriati Sufian

Keyword(s):

Hydrogen Adsorption ◽

Mixed Oxides ◽

Textural Properties ◽

Metal Dispersion ◽

Temperature Programmed Reduction ◽

Oxide Formation ◽

Nickel Cobalt ◽

Icp Ms ◽

Temperature Programmed ◽

Adsorption Desorption

Micro-mesoporous mixed oxides containing nickel, cobalt and aluminum have been synthesized using conventional coprecipitation method. FESEM and HRTEM analyses demonstrated the flower and hexagonal plate-like nanostructured of mixed oxides. Different mixed oxide formation, homogenous metal dispersion, textural properties were investigated using XRD, ICP-MS and BET (N2 adsorption-desorption) techniques. nanostructured mixed oxides exhibited 2.6 wt% hydrogen adsorption that were studied using temperature programmed reduction-adsorption-desorption (H2-TPR/TPD) and thermogravimetric and differential thermal analysis (TGA-DTA) techniques. Investigation corresponds that morphologies, textural properties and surface energy of mixed oxides are important in hydrogen adsorption.

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Effect of High Pressure on the Reducibility and Dispersion of the Active Phase of Fischer–Tropsch Catalysts

Materials ◽

10.3390/ma12121915 ◽

2019 ◽

Vol 12 (12) ◽

pp. 1915 ◽

Cited By ~ 1

Author(s):

Simón Yunes ◽

Miguel Ángel Vicente ◽

Sophia A. Korili ◽

Antonio Gil

Keyword(s):

High Pressure ◽

Physicochemical Characterization ◽

Active Phase ◽

Incipient Wetness Impregnation ◽

X Ray Diffraction ◽

N2 Adsorption ◽

X Ray ◽

Temperature Programmed ◽

Adsorption Desorption

The effect of high pressure on the reducibility and dispersion of oxides of Co and Fe supported on γ-Al2O3, SiO2, and TiO2 has been studied. The catalysts, having a nominal metal content of 10 wt.%, were prepared by incipient wetness impregnation of previously calcined supports. After drying at 60 °C for 6 h and calcination at 500 °C for 4 h, the catalysts were reduced by hydrogen at two pressures, 1 and 25 bar. The metal reduction was studied by temperature-programmed reduction up to 750 °C at the two pressures, and the metal dispersion was measured by CO chemisorption at 25 °C, obtaining values between 1% and 8%. The physicochemical characterization of these materials was completed by means of chemical analysis, X-ray diffraction, N2 adsorption-desorption at −196 °C and scanning electron microscopy. The high pressure lowered the reduction temperature of the metal oxides, improving their reducibility and dispersion. The metal reducibility increased from 42%, in the case of Fe/Al2O3 (1 bar), to 100%, in the case of Fe/TiO2 (25 bar).

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Ru-Promoted Ni/Al2O3 Fluidized Catalyst for Biomass Gasification

Catalysts ◽

10.3390/catal10030316 ◽

2020 ◽

Vol 10 (3) ◽

pp. 316 ◽

Cited By ~ 1

Author(s):

Alan Rubén Calzada Hernandez ◽

Daniel Gibran González Castañeda ◽

Adriana Sánchez Enriquez ◽

Hugo de Lasa ◽

Benito Serrano Rosales

Keyword(s):

Acid Site ◽

Biomass Gasification ◽

Temperature Programmed Desorption ◽

Steam Gasification ◽

Bet Surface Area ◽

Temperature Programmed Reduction ◽

N2 Adsorption ◽

Site Density ◽

Temperature Programmed ◽

Adsorption Desorption

Fluidizable catalysts based on Ni/Al2O3 with added Ru were used for the gasification of a lignin surrogate (2-methoxy-4-methylphenol) in a fluidized CREC Riser Simulator reactor. This was done in order to quantify lignin surrogate conversion and lignin surrogate products (H2, CO, CO2 and CH4) as well as the coke deposited on the catalyst. The catalysts that were evaluated contained 5% wt. Ni with various Ru loadings (0.25%, 0.5% and 1% wt). These catalysts were synthesized using an incipient Ni and Ru co-impregnation. Catalysts were characterized using XRD, N2 adsorption-desorption (BET Surface Area, BJH), Temperature Programmed Reduction (TPR), Temperature Programmed Desorption (TPD) and H2 chemisorption. Catalytic steam gasification took place at 550, 600 and 650 °C using 0.5, 1.0 and 1.5, steam/biomass ratios. The results obtained showed that Ru addition helped to decrease both nickel crystallite site sizes and catalyst acid site density. Moreover, it was observed that coke on the catalyst was reduced by 60%. This was the case when compared to the runs with the Ni/Al2O3 free of Ru.

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Catalytic Performance and Characterization of Ni-Co Bi-Metallic Catalysts in n-Decane Steam Reforming: Effects of Co Addition

Catalysts ◽

10.3390/catal8110518 ◽

2018 ◽

Vol 8 (11) ◽

pp. 518 ◽

Cited By ~ 3

Author(s):

Qinwei Yu ◽

Yi Jiao ◽

Weiqiang Wang ◽

Yongmei Du ◽

Chunying Li ◽

...

Keyword(s):

Steam Reforming ◽

Energy Dispersive Spectrometer ◽

Coke Deposition ◽

Morphological Properties ◽

Temperature Programmed Reduction ◽

N2 Adsorption ◽

High Hydrogen ◽

Hydrogen Selectivity ◽

Temperature Programmed ◽

Adsorption Desorption

Co-Ni bi-metallic catalysts supported on Ce-Al2O3 (CA) were prepared with different Co ratios, and the catalytic behaviors were assessed in the n-decane steam reforming reaction with the purpose of obtaining high H2 yield with lower inactivation by carbon deposition. Physicochemical characteristics studies, involving N2 adsorption-desorption, X-ray diffraction (XRD), H2-temperature-programmed reduction (H2-TPR), NH3 temperature programmed reduction (NH3-TPD), SEM-energy dispersive spectrometer (EDS), and transmission electron microscope (TEM)/HRTEM, were performed to reveal the textural, structural and morphological properties of the catalysts. Activity test indicated that the addition of moderate Co can improve the hydrogen selectivity and anti-coking ability compared with the mono-Ni/Ce-Al2O3 contrast catalyst. In addition, 12% Co showed the best catalytic activity in the series Co-Ni/Ce-Al2O3 catalysts. The results of catalysts characterizations of XRD and N2 adsorption-desorption manifesting the metal-support interactions were significantly enhanced, and there was obvious synergistic effect between Ni and Co. Moreover, the introduction of 12% Co and 6% Ni did not exceed the monolayer saturation capacity of the Ce-Al2O3 support. Finally, 6 h stability test for the optimal catalyst 12%Co-Ni/Ce-Al2O3 demonstrated that the catalyst has good long-term stability to provide high hydrogen selectivity, as well as good resistance to coke deposition.

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The catalytic performances of α-MnO2 and δ-MnO2 catalysts synthesized from KMnO4 and ethanol for total oxidation of isopropanol

Vietnam Journal of Catalysis and Adsorption ◽

10.51316/jca.2020.009 ◽

2020 ◽

Vol 9 (1) ◽

pp. 53-59

Author(s):

Tuan Nguyen Dinh Minh ◽

Nga Phan Thi Hang

Keyword(s):

Low Temperature ◽

Temperature Programmed Reduction ◽

Total Oxidation ◽

Isothermal Adsorption ◽

Catalytic Activities ◽

Oxidation Reduction ◽

Higher Temperature ◽

Temperature Programmed ◽

Adsorption Desorption ◽

Catalytic Performances

In this study, the catalytic activities of total oxidation of isopropanol (IPA) over MnO2-based catalysts (α-MnO2 and δ-MnO2) were studied and compared. These catalysts were synthesized by an oxidation/reduction route between ethanol and KMnO4 by using dropwise method. Their morphological, structural properties, specific surface area, pore distribution and reducibility were characterized by SEM, XRD, FTIR, N2 isothermal adsorption-desorption, and hydrogen temperature-programmed reduction (H2-TPR). As a result, IPA was significantly oxidized to acetone at low temperature (130 °C) and subsequently to CO2 at higher temperature. α-MnO2 was demonstrated as a better catalyst for total oxidation of IPA compared with δ-MnO2. Over 205 °C, IPA was completely oxidized to CO2. Additionally, the high reducibility of δ-MnO2 was found to be correlated with higher activity of IPA toward acetone at low temperature.

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Simultaneous Catalytic Oxidation of a Lean Mixture of CO-CH4 over Spinel Type Cobalt Based Oxides

BULLETIN OF CHEMICAL REACTION ENGINEERING AND CATALYSIS ◽

10.9767/bcrec.15.2.6499.490-500 ◽

2020 ◽

Vol 15 (2) ◽

pp. 490-500

Author(s):

Neha Neha ◽

Ram Prasad ◽

Satya Vir Singh

Keyword(s):

Mixed Oxides ◽

Structural Disorder ◽

Catalytic Performance ◽

Molar Ratio ◽

Total Oxidation ◽

Spinel Type ◽

Molar Ratios ◽

Long Term Stability ◽

Nickel Cobalt ◽

Temperature Programmed

A series of nickel-cobalt bimetal oxides in varying molar ratios and its single metal oxides were synthesized by reactive calcination of coprecipitated basic-carbonates. Several characterization techniques, such as: Bruneuer Emmett Teller (BET), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infra Red (FTIR), and Hydrogen Temperature Programmed Reduction (H2-TPR), were performed over the oxides. Activities of oxides were evaluated in methane total oxidation in the presence or the absence of CO. The best catalytic performance was observed over NiCo catalyst with a Ni/Co molar ratio of 1:1, and the complete conversion of CO-CH4 mixture was achieved at 390 °C. Moreover, the presence of carbon monoxide improves CH4 total oxidation over nickel-cobalt mixed oxides. Structural analysis reveals that the insertion of nickel into the spinel lattice of cobalt oxide causes the structural disorder, which probably caused the increase of the amount of octahedrally coordinated divalent nickel cations that are responsible for catalytic activity. Stability of the best-performed catalyst has been tested in the two conditions, showing remarkable long-term stability and thermal stability, however, showed deactivation after thermally ageing at 700 °C. Copyright © 2020 BCREC Group. All rights reserved

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Bulk Versus Surface Modification of Alumina with Mn and Ce Based Oxides for CH4 Catalytic Combustion

Materials ◽

10.3390/ma12111771 ◽

2019 ◽

Vol 12 (11) ◽

pp. 1771 ◽

Cited By ~ 2

Author(s):

Stefan Neatu ◽

Mihaela M. Trandafir ◽

Adelina Stănoiu ◽

Ovidiu G. Florea ◽

Cristian E. Simion ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Catalytic Combustion ◽

Mixed Oxides ◽

Sol Gel ◽

Nitrogen Adsorption ◽

X Ray Diffraction ◽

X Ray ◽

Temperature Programmed ◽

Catalytic Combustion Of Methane ◽

Adsorption Desorption

This study presents the synthesis and characterization of lanthanum-modified alumina supported cerium–manganese mixed oxides, which were prepared by three different methods (coprecipitation, impregnation and citrate-based sol-gel method) followed by calcination at 500 °C. The physicochemical properties of the synthesized materials were investigated by various characterization techniques, namely: nitrogen adsorption-desorption isotherms, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and H2–temperature programmed reduction (TPR). This experimental study demonstrated that the role of the catalytic surface is much more important than the bulk one. Indeed, the incipient impregnation of CeO2–MnOx catalyst, supported on an optimized amount of 4 wt.% La2O3–Al2O3, provided the best results of the catalytic combustion of methane on our catalytic micro-convertors. This is mainly due to: (i) the highest pore size dimensions according to the Brunauer-Emmett-Teller (BET) investigations, (ii) the highest amount of Mn4+ or/and Ce4+ on the surface as revealed by XPS, (iii) the presence of a mixed phase (Ce2MnO6) as shown by X-ray diffraction; and (iv) a higher reducibility of Mn4+ or/and Ce4+ species as displayed by H2–TPR and therefore more reactive oxygen species.

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Precipitated K-Promoted Co–Mn–Al Mixed Oxides for Direct NO Decomposition: Preparation and Properties

Catalysts ◽

10.3390/catal9070592 ◽

2019 ◽

Vol 9 (7) ◽

pp. 592 ◽

Cited By ~ 3

Author(s):

Květa Jirátová ◽

Kateřina Pacultová ◽

Jana Balabánová ◽

Kateřina Karásková ◽

Anna Klegová ◽

...

Keyword(s):

Catalytic Activity ◽

Mixed Oxides ◽

No Decomposition ◽

Temperature Programmed Reduction ◽

X Ray ◽

Co2 Desorption ◽

Metal Nitrates ◽

Temperature Programmed ◽

Desorption Method ◽

Al Oxide

Direct decomposition of nitric oxide (NO) proceeds over Co–Mn–Al mixed oxides promoted by potassium. In this study, answers to the following questions have been searched: Do the properties of the K-promoted Co–Mn–Al catalysts prepared by different methods differ from each other? The K-precipitated Co–Mn–Al oxide catalysts were prepared by the precipitation of metal nitrates with a solution of K2CO3/KOH, followed by the washing of the precipitate to different degrees of residual K amounts, and by cthe alcination of the precursors at 500 °C. The properties of the prepared catalysts were compared with those of the best catalyst prepared by the K-impregnation of a wet cake of Co–Mn–Al oxide precursors. The solids were characterized by chemical analysis, DTG, XRD, N2 physisorption, FTIR, temperature programmed reduction (H2-TPR), temperature programmed CO2 desorption (CO2-TPD), X-ray photoelectron spectrometry (XPS), and the species-resolved thermal alkali desorption method (SR-TAD). The washing of the K-precipitated cake resulted in decreasing the K amount in the solid, which affected the basicity, reducibility, and non-linearly catalytic activity in NO decomposition. The highest activity was found at ca 8 wt.% of K, while that of the best K-impregnated wet cake catalyst was at about 2 wt.% of K. The optimization of the cake washing conditions led to a higher catalytic activity.

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Highly Active Transition Metal-Promoted CuCeMgAlO Mixed Oxide Catalysts Obtained from Multicationic LDH Precursors for the Total Oxidation of Methane

Catalysts ◽

10.3390/catal10060613 ◽

2020 ◽

Vol 10 (6) ◽

pp. 613

Author(s):

Hussein Mahdi S. Al-Aani ◽

Mihaela M. Trandafir ◽

Ioana Fechete ◽

Lucia N. Leonat ◽

Mihaela Badea ◽

...

Keyword(s):

Electron Microscopy ◽

Transition Metal ◽

Mixed Oxide ◽

Mixed Oxides ◽

Catalytic Performance ◽

Atomic Ratio ◽

Total Oxidation ◽

X Ray ◽

Oxidation Of Methane ◽

Al2o3 Catalyst

To improve the catalytic performance of an active layered double hydroxide (LDH)-derived CuCeMgAlO mixed oxide catalyst in the total oxidation of methane, it was promoted with different transition-metal cations. Thus, two series of multicationic mixed oxides were prepared by the thermal decomposition at 750 °C of their corresponding LDH precursors synthesized by coprecipitation at constant pH of 10 under ambient atmosphere. The first series of catalysts consisted of four M(3)CuCeMgAlO mixed oxides containing 3 at.% M (M = Mn, Fe, Co, Ni), 15 at.% Cu, 10 at.% Ce (at.% with respect to cations), and with Mg/Al atomic ratio fixed to 3. The second series consisted of four Co(x)CuCeMgAlO mixed oxides with x = 1, 3, 6, and 9 at.% Co, while keeping constant the Cu and Ce contents and the Mg/Al atomic ratio. All the mixed oxides were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) coupled with X-ray energy dispersion analysis (EDX), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption-desorption at −196 °C, temperature-programmed reduction under hydrogen (H2-TPR), and diffuse reflectance UV-VIS spectroscopy (DR UV-VIS), while thermogravimetric and differential thermal analyses (TG-DTG-DTA) together with XRD were used for the LDH precursors. The catalysts were evaluated in the total oxidation of methane, a test reaction for volatile organic compounds (VOC) abatement. Their catalytic performance was explained in correlation with their physicochemical properties and was compared with that of a reference Pd/Al2O3 catalyst. Among the mixed oxides studied, Co(3)CuCeMgAlO was found to be the most active catalyst, with a temperature corresponding to 50% methane conversion (T50) of 438 °C, which was only 19 °C higher than that of a reference Pd/Al2O3 catalyst. On the other hand, this T50 value was ca. 25 °C lower than that observed for the unpromoted CuCeMgAlO system, accounting for the improved performance of the Co-promoted catalyst, which also showed a good stability on stream.

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Promotion Effects of La2O3 on Ni/Al2O3 Catalysts for CO2 Methanation

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1118.205 ◽

2015 ◽

Vol 1118 ◽

pp. 205-210 ◽

Cited By ~ 3

Author(s):

Wei Chang Chen ◽

Wen Yang ◽

Jian Dong Xing ◽

Lei Liu ◽

Hong Li Sun ◽

...

Keyword(s):

Particle Size ◽

Impregnation Method ◽

Temperature Programmed Reduction ◽

Active Components ◽

X Ray ◽

Induce Effect ◽

Temperature Programmed ◽

Ni Species ◽

Adsorption Desorption ◽

Catalytic Performances

Ni/Al2O3catalysts improved with different La contents were prepared by the conventional co-impregnation method and characterized by X-ray powder diffraction (XRD), N2adsorption-desorption, H2temperature-programmed reduction (H2-TPR). Catalytic performances for CO2methanation under condition (CO2/H2=4.1:1, 1 atm) were discussed in detail. XRD result demonstrated that the addition of La was in favor of decreasing the Ni particle size and increasing the dispersion of Ni species. The H2-TPR showed that La can change the proportion of various Ni species and increase the content of easily reducible Ni species. These results indicate that La species induce effect, resulting in smaller particle size and weaker interaction between active components and the support, higher dispersions, and reducibility of active phases, ultimately improving catalytic activity of CO2methanation.

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